Hey, thanks for the answer!
Still no luck. Removed all images from the folder, tried downloading, didn't work. Removed DefaultCompany folder, relaunched Joyful, it created it back without issue, tried adding png files in AppData\LocalLow\DefaultCompany\CustomFapHero\fap_images but they don't show up in the downloaded tab (or the searched tab, not that they would).
So yeah essentially it fails at saving url images and can't download at all. I also tried filling the full gallery page with images but same result.